Pulp digester



JIM/mm fi/nan kiwi/ y Q (W I E. MORTERUD PUL DIGFSTER Filed Oct. 10, 1929 Sept. 3U, 1930.

'45 opening with the object Patented Sept. 30, 1930 NETED TATES FFKIE PULP DIGESTER Application filed October 10, 1929. Serial No. 398,751.

The present invention relates to pulp digesters of the kind in which there is provided in the interior of the digester circulation pipes co-operating with screens or sieves for maintaining a continuous circulation of the liquor or other liquid inside the digester.

In accordance with one feature of the present invention the digester is provided approx imately at the middle with an annular screen,

the diameter of which is considerably smaller than the interior diameter of the digester, and which is supported from the wall of the digester by means of stays or the like, so as to be held in a horizontal position a certain dis is tance from the interior wall of the digester.

Said annular screen or sieve which may bein the form of a circular or polygonal tube sieve, communicates with the suction side of the circulation pump, which is preferably mounted inside the digester near the middle of the same.

The suction side of said circulation pump may also communicate with a second annular screen or sieve mounted substantially in the same plane as the first mentioned screen or sieve tube on the inner wall of the digester.

According to a further feature of the in vention the circulation pump is provided with two pressure or outlet openings com- 3 mumcatmg w th circulation pipes extending upwards and downwards to the top and bottom of the digester respectively, so as to distribute the liquid sucked up from the middle part of the digester to the upper and lower part thereof respectively.

Dampers or valves may be provided in the two outlet pipes from the circulation pump in order to regulate the distribution of the liquid circulated.

According to a further feature of'the invention the downwardly extending circulation pipe communicates with a screen or sieve tube secured to the conical bottom part/of the digester and pointing against the outlet providing the least possible obstruction to the removal of the digested pulp.

According to a further feature of the invention a second sieve or screen tube ma be located at the upper part of the conical otthat the pump tom section of the digester, said circular sieve or screen tube communicating with the downwardly extending pressure outlet from the circulation pump, a valve or the like being provided for directing the liquid from the circulation pump either to one or the other of said sieves.

Said circular sieve tube at the upper part of the conical bottom section of the digester serves the object of providing a film of liquid along the conical bottom surface of the digester to'prevent pulp sticking to said bottom surface when the digester is emptied.

An embodiment of the invention is illustrated on the drawing, where Fig. 1 is a vertical axial section through a digester comprising the improvements according to the invention.

Fig. 2 is a cross section on the line 11-11 of 'Fig. 1.

Fig. 3 is a horizontal section on a larger scale through the circulation pump, and 1 {Fig 4 is a view of Fig. 3 as seen from the The digester 1 is provided near its middle with an annular sieve tube 2 secured to the digester wall by means of stays 3, in the same plane as said sieve tube 2 there is also located along the interior wall of the digester a second sieve tube 4, and both sieve tubes 2 and 4 communicate with the suction intake of the circulation pump 5.

The circulation pump 5 is provided, as is best seen on Fig. 4, with two outlets 6, 6, communicating with an upwardly extending pipe 8 and a downwardly extending pipe 9. Dampers 10 may be provided in the inlet channels as well as in the outlet channels of the circulation pump in order to regulate the circulation.

A circular pressure sieve 11 is located near the top of the conical bottom section of the digester, said pressure sieve communicating by means-of valve 12 with the downwardly extending pressure tube 9, but it is obvious may also have a special outlet for supp ying liquid to said pressure sieve 11.

Sieves 13 and 14 communicate with the free ends of pressure tubes 8 and 9, and

serve to distribute the liquid circulated by the pump 5. In order to afford as little obstruction as possible to the emptying of the digester, the sieve 14 located at the bottom of the digester is rectilinear and oints towards the outlet opening 15 of the 'gester.

Claims.

1. In a digester for wood pulp circulation pipes for circulating liquid through the digester, a mechanically driven pump for carrying liquid through said circulatlon pipes, outlet sieves adjacent the top and bottom of said di ester communicating with the pressure si e of said pump and an intake sieve comprisin adjacent the central part of the digester at a distance from the walls thereof and communicating with the intake side of said circulation pump.

' 2. In a digester for wood pulp circulation pipes for circulatin liquid through the digester, a mechanical y driven pump for carrying liquid through said circulation pipes, outlet sieves adjacent the top and bottom of said di ter communicating with the pressure si e of said pump, an intake sieve comrising an annular sieve tube supported adacent the central part of the digester at a distance from the walls thereof and com-u municating with the intake side of said cir culation pump and a second annular intake sieve located substantially in the same plane as the said first mentioned intake sieve and communicating with the intake side of said circulation pump;

3. In a digester for wood pulp circulation pipes for circulating liquid through the digester, a mechanically driven pump for carrying liquid through saidcirculation pipes, outlet sieves adjacent the top and bottom of said digester communicating with the pres sure side of said pump, an intake sieve comprising an annular sieve tube supported adj acent the central part of the digester at a distance from the walls thereof and communicating with the intake side of said circulation pump, a second annular intake sieve located substantially in the same plane as the said first mentioned intake sieve and communicating with the intake side of said circulation pump and means for controlling the suction effect in said intake sieves.

4. In a digester for wood pulp circulation pipes for circulating liquid through the diester, a mechanically driven pump for carrying liquid through said circulation pipes, said ump being provided with two outlet 0 enings, outlet sieves adjacent the top and ottom of said digester communicating with the two outlet openings of said circulation pump and an intake sieve comprising an annular sieve tube supported adjacent the central part of the digester at a distance from the walls thereof and communicating with the intake side of said circulation pump.

an annular sieve tube supported 5. In a digester for wood pulp circulation pipes for circulating liquid through the digester, ainechanically driven pump for carrying liquid through said circulation pipes, said pump being provided with two outlet openings, outlet sieves adjacentthe top and bottom of said digester communicating with the two outlet openings of said circulation pump, means for regulating the amount of li uid carried to said outlet sieves and an inta e sieve comprising an annular sieve tube supported adjacent the central part of the digester at a distance from the walls thereof and communicating with the intake side of said circulation pump.

6. In a digester for wood pulp circulation pipes for circulating liquid through the digester, a mechanically driven pump for carrying liquid through said circulation pipes, said pump being provided with two outlet openings, one outlet sieve adjacent the top of said digester, a second outlet sieve near the bottom of the digester and a third outlet sieve in the form of an annular tube located at the top of the conical bottom part of the digester and means for directing the liquid from the pump to one or more of said outlet sieves.-

7 In a digester for wood pulp circulation pipes for circulating liquid through the'digester, a mechanically driven pump for carrying liquid through said circulation pipes, said pump being provided with two outlet openings, an outlet sieve in the form of a substantially straight tube located near the bottom of the digester, a second outlet sieve in the form of an annular tube located near the upper end of the conical bottom part of the digester and'means for directing liquidto either of said two outlet sieves.

In testimony whereof I affix my signature.

EINAR -MORTERUD. 

